Uber said the number of taxis are limited for now. "Many taxis don't fit Uber standards, so we are curating our supply pretty carefully," the blog reads.

Uber lets users order cars through its app and put all charges onto an on-file credit card. To request a taxi instead of the usual black sedan, customers need to select "TAXI" in the Uber app. Standard taxi fees apply, and a 20 percent gratuity will be automatically added to charges.